Mineral wool composition

ABSTRACT

Mineral wool capable of dissolving in a physiological medium, and which comprises fibers whose constituents are mentioned below in the following percentages by weight:  
                                                   SiO 2     35-60%,    preferably   39-55%          Al 2 O 3     12-27%,    ″   16-25%          CaO   0-35%,   ″   3-25%         MgO   0-30%,   ″   0-15%         Na 2 O   0-17%,   ″   6-12%         K 2 O   0-17%,   ″   3-12%         R 2 O (Na 2 O + K 2 O)   10-17%,    ″   12-17%          P 2 O 5     0-5%,    ″   0-2%          Fe 2 O 3     0-20%,         B 2 O 3     0-8%,    ″   0-4%          TiO 2     0-3%,                                         
 
     and also comprises a phosphorus compound, the phosphorus content of which, expressed in P 2 O 5  form, varies from 0.2%, especially from more than 0.5%, to 5%, especially to less than 2%, of the total mass of fibers, which is capable of reacting above 100° C. with the fibers to form a coating on the surface of the fibers.

[0001] The present invention relates to the field of artificial mineralwools. It is aimed more particularly at mineral wools intended formanufacturing thermal and/or acoustic insulation materials orsoilless-culture substrates. It relates in particular to thermallystable mineral wools intended for applications in which the capabilityof withstanding temperature is important.

[0002] These mineral wools are capable of playing an important role inthe fire resistance of structural systems into which they have beenincorporated.

[0003] It concerns more particularly mineral wools of the rock-wooltype, that is to say the chemical compositions of which wools involve ahigh liquidus temperature and a high fluidity at their fiberizingtemperature, combined with a high glass transition temperature.

[0004] Conventionally, this type of mineral wool is fiberized byprocesses called “external” centrifuging, for example of the type ofthose using a cascade of centrifuging wheels fed with molten material bya static delivery device, as described in particular in PatentsEP-0,465,310 or EP-0,439,385.

[0005] The process called “internal” centrifuging fiberizing, that is tosay the process using centrifuges rotating at high speed and drilledwith holes, is, on the other hand, conventionally reserved forfiberizing mineral wool of the glass-wool type, schematically having acomposition richer in alkali metal oxides and having a low aluminacontent, a lower liquidus temperature and a higher viscosity at thefiberizing temperature than rock wool. This process is described, inparticular, in Patent EP-0,189,354 or Patent EP-0,519,797.

[0006] However, technical solutions have recently been developed whichmake it possible to adapt the internal centrifuging process to thefiberizing of rock wool, especially by modifying the composition of theconstituent material of the centrifuges and their operating parameters.For further details on this subject, reference may be made especially toPatent WO 93/02977. This adaptation has proved to be particularlybeneficial in the sense that it allows properties which hitherto wereonly inherent in one or other of the two types of wool—rock wool orglass wool—to be combined. Thus, the rock wool obtained by internalcentrifuging has a quality comparable to that of glass wool, with alower content of unfiberized material than rock wool obtainedconventionally. However, it retains the two major advantages associatedwith its chemical nature, namely a low chemicals cost and a hightemperature withstand capability.

[0007] There are therefore now two possible ways of fiberizing rockwool, the choice of one or other depending on a number of criteria,including the quality level required for the intended application andthe level of industrial and economic feasibility.

[0008] To these criteria have in recent years been added that ofbiodegradability of mineral wool, namely its ability to be rapidlydissolved in a physiological medium, so as to prevent any potentialpathogenic risk associated with the possible accumulation of the finestfibres in the body by inhalation.

[0009] Furthermore, many mineral wool applications use the remarkableproperty of thermal stability that certain mineral wool compositionsexhibit. In particular, the thermal stability of mineral wools obtainedfrom basalt or from iron-enriched slag, is known.

[0010] The drawback of these compositions is, in the case of basalt, itslow solubility in a physiological medium and, in the case ofiron-enriched slag, its high fiberizing temperature which limits theprocess for fiberizing these compositions using processes called“external” processes.

[0011] One solution to the problem of choosing the composition of arock-type mineral wool having a biosoluble nature consists in the use ofa high content of alumina and moderate alkali contents.

[0012] This solution results in particular in high raw materials costsbecause of the preferred use of bauxite.

[0013] The object of the present invention is to improve the chemicalcomposition of rock-type mineral wool fibers, the improvement beingaimed especially at increasing their biodegradability with the abilityfor them to be fiberized especially and advantageously by internalcentrifuging, while still maintaining the possibility of obtaining thesecompositions from inexpensive raw materials and of giving these mineralwools excellent thermal stability.

[0014] The expression “thermally stable mineral wool” or “woolexhibiting thermal stability” should be understood to mean a mineralwool capable of exhibiting temperature resistance, that is to saycapable of not collapsing when it is heated, especially up totemperatures of at least 1000° C.

[0015] In particular, a mineral wool is regarded as being thermallystable if it meets the criteria defined by the draft standard“Insulating materials: Thermal stability” as proposed by NORDTEST (NTFIRE XX—NORDTEST REMISS No.1114-93).

[0016] This test defines a procedure for determining the thermalstability of a specimen of insulating material at a temperature of 1000°C. A specimen of insulating material (especially 25 mm in height and 25mm in diameter) is put into a furnace which allows the collapse of thespecimen to be observed as a function of the temperature of thespecimen.

[0017] The temperature of the furnace is increased from room temperatureup to at least 1000° C. at a rate of 5° C. per minute.

[0018] This draft standard defines an insulating material as beingthermally stable if the specimen of this material does not collapse bymore than 50% of its initial thickness until the temperature of 1000° C.has been reached.

[0019] The subject of the invention is a mineral wool capable ofdissolving in a physiological medium, which comprises fibers whoseconstituents are mentioned below in the following percentages by weight:SiO₂ 35-60%,  preferably 39-55%  Al₂O₃ 12-27%,  ″ 16-25%  CaO 0-35%, ″3-25% MgO 0-30%, ″ 0-15% Na₂O 0-17%, ″ 6-12% K₂O 0-17%, ″ 3-12% R₂O(Na₂O + K₂O) 10-17%,  ″ 12-17%  P₂O₅ 0-5%,  ″ 0-2%  Fe₂O₃ 0-20%, B₂O₃0-8%,  ″ 0-4%  TiO₂ 0-3%, 

[0020] and also comprises a phosphorus compound, the phosphorus contentof which, expressed in P₂O₅ form, varies from 0.2%, especially from morethan 0.5%, to 5%, especially to less than 2%, of the total mass offibers, which is capable of reacting above 100° C. with the fibers toform a coating on the surface of the fibers.

[0021] It has in fact been found that, surprisingly, the fibers, theconstituents of which are selected above, react with phosphoruscompounds above 100° C. and that this reaction can continue when thetemperature is increased. The formation of a coating on the surface ofthe fibers, especially on fibers that have been heated to temperaturesof about 1000° C., is observed.

[0022] This coating has the remarkable property of being refractory andthus retards the collapse of a fiber specimen, of the selectedcomposition, heated to temperatures possibly up to 1000° C.

[0023] The compound, resulting from the reaction between the fiberconstituents and the phosphorus compounds, is rich in phosphorus.Phosphorus contents of between 40 and 60 at % are especially observed inthis compound.

[0024] The observed coating may be continuous over the surface of afiber and its thickness is especially between 0.01 and 0.05 μm.Crystallization of a composition similar to that of the coating may alsobe observed locally on the surface of the fibers and thicknesses ofabout 0.1 to 0.5 μm may be reached.

[0025] It is demonstrated that there is a cooperative effect between thefibers, having been the subject of the above selection of constituents,and phosphorus compounds. Thus, mineral wools are obtained which arecapable of dissolving in a physiological medium and are thermallystable.

[0026] According to a variant of the invention, the mineral woolcomprises fibers whose constituents are mentioned below in the followingpercentages by weight: SiO₂ 39-55%,  preferably 40-52%  Al₂O₃ 16-2%,  ″16-25%  CaO 3-35%, ″ 10-25%  MgO 0-15%, ″ 0-10% Na₂O 0-15%, ″ 6-12% K₂O0-15%, ″ 3-12% R₂O (Na₂O + K₂O) 10-17%,  12-17%  P₂O₅ 0-5%,  ″ 0-2% Fe₂O₃ 0-15%, B₂O₃ 0-8%,  ″ 0-4%  TiO₂ 0-3%, 

[0027] and when MgO is between 0 and 5%, especially between 0 and 2%,R₂O≦13.0%.

[0028] According to one advantageous embodiment of the invention, themineral wool comprises fibers whose constituents are mentioned below inthe following percentages by weight: SiO₂ 39-55%,  preferably 40-52% Al₂O₃ 16-25%,  ″ 17-22%  CaO 3-35%, ″ 10-25%  MgO 0-15%, ″ 0-10% Na₂O0-15%, ″ 6-12% K₂O 0-15%, ″ 6-12% R₂O (Na₂O + K₂O) 13.0-17%,   ″ P₂O₅0-5%,  ″ 0-2%  Fe₂O₃ 0-15%, B₂O₃ 0-8%,  ″ 0-4%  TiO₂ 0-3%. 

[0029] In the rest of the text, the word “composition” refers to theranges of the constituents of the fibers of the mineral wool, or of theglass intended to be fiberized in order to produce said fibers.

[0030] In the rest of the text, any percentage of a constituent of thecomposition should be understood to mean a percentage by weight and thecompositions according to the invention may include up to 2 or 3% ofcompounds to be considered as unanalyzed impurities, as is known in thiskind of composition.

[0031] The selection of such a composition has allowed a whole raft ofadvantages to be combined, especially by varying the many and complexroles that a number of these specific constituents play.

[0032] It has in fact been possible to show that the combination of ahigh alumina content, of between 16 and 27%, preferably greater than 17%and/or preferably less than 25%, especially less than 22%, for a sum ofnetwork formers—silica and alumina—of between 57 and 75%, preferablygreater than 60% and/or preferably less than 72%, especially less than70%, with a high amount of alkalis (R₂O: soda and potash) of between 10and 17%, with an MgO content of between 0 and 5%, especially between 0and 2%, when R₂O≦13.0%, makes it possible to obtain glass compositionshaving the remarkable property of being fiberizable over a very widetemperature range and of endowing the fibers obtained with biosolubilityat acid pH. Depending on the embodiments of the invention, the alkalicontent is preferably greater than 12%, especially greater than 13.0%and even 13.3%, and/or preferably less than 15%, especially less than14.5%.

[0033] This range of compositions proves to be particularly beneficialas it has been possible to observe that, contrary to the receivedopinions, the viscosity of the molten glass does not drop significantlywith increasing alkali content. This remarkable effect makes it possibleto increase the difference between the temperature corresponding to theviscosity for fiberizing and the liquidus temperature of the phase whichcrystallizes, and thus to considerably improve the fiberizingconditions, and especially makes it possible to fiberize a new family ofbiosoluble glasses by internal centrifuging.

[0034] According to one embodiment of the invention, the compositionshave iron oxide contents of between 0 and 5%, especially greater than0.5% and/or less than 3%, especially less than 2.5%. Another embodimentis obtained with compositions which have iron oxide contents of between5 and 12%, especially between 5 and 8%, which may allow mineral-woolblankets to exhibit fire resistance.

[0035] Advantageously, the compositions according to the inventionsatisfy the ratio:

[0036] (Na₂O+K₂O)/Al₂O₃≧0.5, preferably (Na₂O+K₂O)/Al₂O₃≧0.6, especially(Na₂O+K₂O)/Al₂O₃≧0.7, which appears to favor the obtaining of atemperature corresponding to the viscosity for fiberizing which isgreater than the liquidus temperature.

[0037] According to a variant of the invention, the compositionsaccording to the invention preferably have a lime content of between 10and 25%, especially greater than 12%, preferably greater than 15% and/orpreferably less than 23%, especially less than 20%, and even less than17%, combined with a magnesia content of between 0 and 5%, withpreferably less than 2% magnesia, especially less than 1% magnesiaand/or a magnesia content of greater than 0.3%, especially greater than0.5%.

[0038] According to another variant, the magnesia content is between 5and 10% for a lime content of between 5 and 15%, and preferably between5 and 10%.

[0039] Adding P₂O₅, which is optional, at contents of between 0 and 3%,especially greater than 0.5% and/or less than 2%, may allow thebiosolubility at neutral pH to be increased. Optionally, the compositionmay also contain boron oxide which may allow the thermal properties ofthe mineral wool to be improved, especially by tending to lower itscoefficient of thermal conductivity in the radiative component and alsoto increase the biosolubility at neutral pH. Optionally, TiO₂ may alsobe included in the composition, for example up to 3%. Other oxides, suchas BaO, SrO, MnO, Cr₂O₃ and ZrO₂, may be present in the composition,each up to contents of approximately 2%.

[0040] The difference between the temperature corresponding to aviscosity of 10^(2.5) poise (decipascal.second), denoted T_(log 2.5),and the liquidus of the crystallizing phase, denoted T_(liq), ispreferably at least 10° C. This difference, T_(log 2.5)−T_(liq), definesthe “working range” of the compositions of the invention, that is to saythe range of temperatures within which it is possible to fiberize, mostparticularly by internal centrifuging. This difference is preferably atleast 20 or 30° C., and even more than 50° C., especially more than 100°C.

[0041] The compositions according to the invention have high glasstransition temperatures, especially greater than 600° C. Their annealingtemperature (denoted T_(annealing)) is especially greater than 600° C.

[0042] As mentioned above, the mineral wools have a satisfactory levelof biosolubility, especially at acid pH. Thus, they generally have arate of dissolution, especially measured with regard to silica, of atleast 30 and preferably of at least 40 or 50 ng/cm² per hour measured atpH 4.5.

[0043] Another very important advantage of the invention concerns thepossibility of using inexpensive raw materials for obtaining thecomposition of these glasses. These compositions may especially resultfrom the melting of rocks, for example of the phonolite type, with analkaline-earth carrier, for example limestone or dolomite, if necessarysupplemented with iron ore. By this means, an alumina carrier ofmoderate cost is obtained.

[0044] This type of composition, having a high alumina content and ahigh alkali content, may be advantageously melted in fired or electricglass furnaces.

[0045] According to one advantageous embodiment of the invention, thecoating capable of forming on the surface of the mineral wool fibersessentially consists of an alkaline-earth phosphate.

[0046] Thus, coatings whose composition is similar to that of crystalsof the alkaline-earth orthophosphate or pyrophosphate type, the meltingpoint of which is known as being above 1000° C., are obtained.

[0047] Advantageously, the alkaline-earth phosphate which is capable offorming on the surface of the mineral wool fibers is a calciumphosphate.

[0048] Calcium phosphates, especially the orthophosphate (Ca₃(PO₄)₂) andthe pyrophosphate (Ca₂P₂O₇), are known to be refractory and thesecompounds have melting points of 1670° C. and 1230° C., respectively.

[0049] According to a variant of the invention, the phosphorus compoundcapable of reacting with the fibers is a compound which decomposes above100° C., releasing phosphoric acid (H₃PO₄, HPO₃, etc.) and/or phosphoricanhydride (P₂O₅), in solid, liquid or vapor form.

[0050] According to a preferred embodiment, the phosphorus compound ischosen from the following compounds:

[0051] ammonium salts, ammonium phosphates, especially ammonium hydrogenphosphate (called AHP), ammonium dihydrogen phosphate (called ADP) andpolyphosphates (especially of the metaphosphate and pyrophosphatetypes).

[0052] These ammonium salts may be pure or may include organic radicals;

[0053] phosphoric acid in its various forms, especially orthophosphoricacid (H₃PO₄), metaphosphoric acid and polyphosphoric acid ([HPO₃]_(n));

[0054] aluminum hydrogenophosphates, especially aluminum hydrogenphosphate or aluminum dihydrogen phosphate, by themselves or mixed withorthophosphoric acid.

[0055] The invention also relates to a process for manufacturing mineralwool in which fibers are essentially formed from molten oxides whoseconstituents are mentioned below in the following percentages by weight:SiO₂ 35-60%,  preferably 39-55%  Al₂O₃ 12-27%,  ″ 16-25%  CaO 0-35%, ″3-25% MgO 0-30%, ″ 0-15% Na₂O 0-17%, ″ 6-12% K₂O 0-17%, ″ 3-12% R₂O(Na₂O + K₂O) 10-17%,  ″ 12-17%  P₂O₅ 0-5%,  ″ 0-2%  Fe₂O₃ 0-20%, B₂O₃0-8%,  ″ 0-4%  TiO₂ 0-3%, 

[0056] and in which a phosphorus compound, capable of reacting with thefibers in order to form a coating on the surface of the fibers, is thenapplied, especially by spraying or impregnating with a solution.

[0057] The invention also relates to the use of the mineral wooldescribed above in fire-resistant structural systems.

[0058] The expression “fire-resistant structural systems” is understoodto mean systems comprising, in general, assemblies of materials,especially those based on mineral wool and metal sheets or plates, whichare capable of effectively retarding the propagation of heat, ofproviding protection against flames and hot gases and of retainingmechanical strength in a fire.

[0059] Standardized tests define the degree of fire resistance,especially expressed as the time needed for a given temperature to reachthe opposite side of the structural system subjected to a heat flux,generated for example by the flame of a burner or an electric furnace.

[0060] A structural system is regarded as exhibiting satisfactory fireresistance in particular if it can meet the requirements of one of thefollowing tests:

[0061] fire door testing: tests on sheets of mineral fibers, as definedin the German Standard DIN 18 089-Part 1;

[0062] fire behavior of material and of structural components, asdefined in German standard DIN 4102. In particular, German standard DIN4102-Part 5 for full-scale testing, in order to determine the fireresistance class, and/or German standard DIN 4102-Part 8 for testingspecimens on a small test bed are considered;

[0063] testing according to the standardized OMI A 754 (18) test, whichdescribes the general requirements of fire resistance tests for“MARINE”-type applications, especially for bulkheads on ships. Thesetests are carried out on large-sized specimens, in furnaces measuring 3m by 3 m. Mention may be made, for example, of the case of a steel deckwhere the required performance in the case of a fire on the insulationside is to meet the thermal insulation criterion for at least 60minutes.

[0064] Further details and advantageous characteristics will becomeapparent from the description below of nonlimiting preferredembodiments.

[0065] Table 1 below gives the chemical compositions, in percentages byweight, of forty-two examples.

[0066] When the sum of all the contents of all the compounds is slightlyless or slightly greater than 100%, it should be understood that thedifference from 100% corresponds to the impurities/minor components thatare not analyzed and/or is due only to the approximation accepted inthis field in the analytical methods used.

[0067] The compositions according to these examples were fiberized byinternal centrifuging, especially according to the teaching of theaforementioned patent WO 93/02977.

[0068] Their working ranges, defined by the difference T_(log)2.5−T_(liq) are well positive, especially greater than 50° C., or even100° C., and even greater than 150° C.

[0069] All the compositions have a (Na₂O+K₂O)/Al₂O₃ ratio greater than0.5 for a high alumina content of about 16 to 25%, with quite a high(SiO₂+Al₂O₃) sum and an alkali content of at least 10% when MgO is lessthan or equal to 5% and of at least 13% when MgO is greater than 5%.

[0070] The liquidus temperatures are not very high, especially less thanor equal to 1200° C. and even 1150° C.

[0071] The temperatures corresponding to viscosities of 10^(2.5) poise(T_(log 2.5)) are compatible with the use of high-temperature fiberizingdishes, especially under the operating conditions described inapplication WO 93/02977.

[0072] The preferred compositions are particularly those in whichT_(log 2.5) is less than 1350° C., preferably less than 1300° C.

[0073] It has been observed that, for the compositions comprisingbetween 0 and 5% of magnesia MgO, especially with at least 0.5% MgOand/or less than 2%, or even less than 1%, MgO, and between 10 and 13%of alkalis, very satisfactory results in respect of physical properties,especially working ranges and dissolution rates, are obtained (as in thecase of the following examples: Ex. 18, Ex. 31, Ex. 32 and Ex. 33).

[0074] To illustrate the present invention, various components wereadded during the fiberizing process, by spraying them in a zone locatedafter the zone in which the fibers are drawn from the molten glass butbefore the zone for collecting the mineral wool. The term “additives”refers to the compounds added in this spraying zone.

[0075] By way of examples, the four compositions in Table 1, denoted Ex.4, EX. 33, EX. 41 and EX. 42, were fiberized with and without aphosphorus-based compound in order to obtain mineral wool blankets.

[0076] A control glass, the contents of the elements of which lieoutside the range selected for the present invention, was also fiberizedwith and without a phosphorus-based compound. This glass is called“CONTROL” and its composition (in percentages by weight) is as follows:

[0077] SiO₂: 65%; Al₂O₃: 2.1%; Fe₂O₃: 0.1%; CaO: 8.1%; MgO: 2.4%; Na₂O:16.4%; K₂O: 0.7%; B₂O₃: 4.5%.

[0078] It should be noted that the additives may include compounds addedsimultaneously or separately. In the tests below, given in Table II anddenoted “TEST”, the additive comprises a resin-based binder and forcertain examples a phosphorus compound added to this binder and sprayedat the same time as the latter. A test was carried out in the absence ofbinder, only the phosphorus compound being sprayed (the test referred toas “TEST 14”).

[0079] The mineral wools obtained were examined and their density (ρ,expressed in kg/m³) and their thermal stability were measured. Tomeasure the thermal stability, mineral wool specimens about 25 mm inheight and 25 mm in diameter were taken from the mineral wool blanket.The collapse of these specimens was measured in accordance with theprocedure defined above under the title “Insulating materials: thermalstability”. Table II gives the values of the degree of collapse measuredat 1000° C. The term “relative thickness” is understood to mean theresidual thickness of the specimen measured at a given temperature withrespect to the initial thickness of the specimen (at room temperature).The term “degree of collapse” is the value of (1−“relative thickness”)at the given temperature.

[0080] Table II gives the results of the tests carried out. Thevariables measured on the specimens are: the composition of the fibers,the density of the mineral wool (ρ) and the additive (type and amountsprayed). The result indicative of the thermal stability, measured andgiven in Table II, is the degree of collapse at 1000° C.

[0081] To illustrate the method of determining the degree of collapse at1000° C., FIG. 1 shows the measured variation in the relative thicknessof mineral wool specimens as a function of temperature from 500° C. to1000° C. This shows that the specimen labeled “TEST 6” suddenlycollapses above 700° C. to 750° C. and that the relative thickness isless than 25% above 880° C. Such a specimen is said to be thermallyunstable since its degree of collapse at 1000° C. is about 75%. Unlikethis specimen, the specimens corresponding to “TEST 10”, “TEST 11” and“TEST 16” in FIG. 1 undergo moderate collapse above 700-750° C., andthen their collapse stabilizes around 900° C. They may therefore be saidto have a “collapse plateau”. These three specimens (“TEST 10”, “TEST11” and “TEST 16”) have a degree of collapse of 26%, 28% and 18%,respectively. Since these degrees of collapse are less than 50%, themineral wools from which the specimens were taken are termed thermallystable.

[0082] The additives added in the spraying zone are of two kinds:

[0083] resin-based binders, well known in the mineral wool field. Thefunction of these binders is to give the mineral wool blanket thedesired mechanical strength. Two binders were studied for the presenttrials: a binder based on a phenol-formaldehyde resin with urea(standard binder) with reference D in Table II and a melamine-basedbinder with reference E in Table II, and known for providing thermalstability advantages;

[0084] phosphorus compounds, the advantage of which for favoring orincreasing the thermal stability of mineral wools consisting of fibersof the composition according to the invention will be demonstrated.

[0085] The phosphorus compounds presented in Table II are three innumber:

[0086] a nonpermanent fire retardant known by the brand name “FLAMMETINUCR-N” and produced by Thor Chemie. This compound has the reference B intable II. This product is used for fireproofing cotton-, cellulose- andpolyester-based textiles. It comprises ammonium phosphates. The amountof phosphorus, expressed in P₂O₅, form, of this product may be estimatedto be about 40% of the mass of the product;

[0087] a fire retardant known by the brand name “FLAMMENTIN TL 861-1”and produced by Thor Chemie. This compound has the reference A in TableII. This product consists of a mixture of around 30 to 40% of FLAMMENTINUCR-N (A) and an organic compound (especially of the acrylic type). Theamount of phosphorus, expressed in P₂O₅ form, is around 15 to 20% of themass of the product. These two products, A and B, are intended fortextile applications and also include blowing agents, desiccants (and,in very small quantities, wetting agents, dispersants, setting agents,softeners and enzymes). They constitute intumescent formulations,especially due to the formation of a protective foam layer;

[0088] a phosphorus compound with reference C in Table II, namelyammonium dihydrogen phosphate (denoted by “ADP”). This compoundcontributes about 55% by weight of phosphorus, expressed as P₂O₅.

[0089] The results given in Table II demonstrate that:

[0090] the addition of a phosphorus compound, the phosphorus content,expressed as P₂O₅, of which is between 0.2 and 5%, makes it possible toobtain thermally stable mineral wools whose fiber compositioncorresponds to the range of contents selected for the present invention;

[0091] a mineral wool whose fiber composition does not lie within theselected range is not thermally stable, even with the addition of aphosphorus compound within the contents according to the invention (see“TEST 2”);

[0092] the degree of collapse at 1000° C. of the mineral wool comprisingfibers according to the invention decreases as the amount of P₂O₅increases. However, the effect of the phosphorus compound is verysignificant even at low P₂O₅ contents: the amount of P₂O₅ is around 0.5%in the case of the “TEST 12” test and around 0.8% in the case of the“TEST 9”, “TEST 13” and “TEST 26” tests. It should also be noted thatthe effect of the phosphorus reaches a threshold at around 2 to 3% P₂O₅(compare “TEST 19” with “TEST 20”);

[0093] the binder has very little effect on the thermal stability ofmineral wools according to the invention and excellent results areobtained even with no binder (“TEST 14”).

[0094] Among the advantages of the invention is the possibility of usinga very simple phosphorus compound, which is distinguished fromintumescent compositions. A very significant cost advantage is thusobtained and it is necessary to handle a much smaller amount ofmaterial. Furthermore, it has been demonstrated that phosphoruscompounds which decompose easily in phosphoric acid are miscible withthe binders conventionally used in the mineral wool industry, thusmaking it possible to simultaneously spray a binder and the phosphoruscompound capable of reacting with the glass fibers according to theinvention.

[0095] The mineral wool specimens obtained after the thermal stabilitytest, i.e. after they have reached a temperature of 1000° C., wereexamined.

[0096] It was noticed that the fibers of the mineral wool specimensaccording to the invention were relatively well preserved and that theyhad not melted.

[0097] Observations using microanalytical techniques, especiallyscanning electron microscopy with elemental analysis (by EDX) and an ionprobe (SIMS) have demonstrated that there is an almost continuouscoating on the surface of the fibers. Typically, this coating has athickness of 0.01 to 0.05 μm. Its composition is essentially based onphosphorus and calcium. The presence of magnesium and/or iron was notedin some of the specimens.

[0098] Fibers sampled after a temperature rise up to 600° C. were alsofound to have a coating of the same type as that existing attemperatures below 1000° C.

[0099] Without wishing to be tied to one scientific theory, it isconceivable that the phosphorus compound releases, especially above 100°C., phosphoric acid and/or phosphoric anhydride which starts to reactwith the fibers of the composition according to the invention. In thecase of these compositions, their high alkali content may play a role incompensating for the charge of aluminum, also present in high amounts.The atomic mobility of alkaline-earth elements in the compositions wouldthus be higher than that of these elements in other glass compositions.These relatively mobile alkaline-earth elements would then be capable ofreacting with the phosphoric acid or phosphoric anhydride, to form arefractory compound, especially an alkaline-earth phosphate, and wouldthus provide the mineral wools according to the invention with excellentthermal stability.

[0100] Advantageously, the mineral wools according to the invention aresuitable for all the usual applications of glass wool and rock wool.TABLE I EX. 1 EX. 2 EX. 3 EX. 4 EX. 5 EX. 6 EX. 7 EX. 8 EX. 9 SiO₂ 47.742.6 44.4 45.2 45.4 43.9 44.2 43.8 46.1 Al₂O₃ 18.6 18.1 17.3 17.2 18.117.6 17.6 17.6 17.4 CaO 6.2 22.7 21.7 15.3 13.5 15 13.3 14.2 13.2 MgO7.1 0.2 0.4 0.5 0.5 0.5 0.5 0.5 0.5 Na₂O 8.0 6.3 6.0 6.2 6.5 6.40 6.36.4 6.3 K₂O 5.2 7.4 7.1 7.8 8.1 7.6 7.9 7.9 7.8 Fe₂O₃ 7.2 2.5 3 6.6 7.38.4 9.8 9.2 8.3 TOTAL 100 99.8 99.9 98.8 99.4 99.4 99.6 99.6 99.6 SiO₂ +Al₂O₃ 66.3 60.7 61.7 62.4 63.5 61.5 61.8 61.4 63.5 Na₂O + K₂O 13.2 13.713.1 14 14.6 14.2 14.2 14.3 14.1 (Na₂O + K₂O)/Al₂O₃ 0.71 0.76 0.76 0.810.81 0.81 0.81 0.81 0.81 T_(log 2.5) (in ° C.) 1293 1239 1230 1248 12801270 1285 1275 1310 T_(liq) (in ° C.) 1260 1200 1190 1160 1160 1120 11001110 1140 T_(log 2.5) − T_(liq) (in ° C.) +33 +39 +40 +88 +120 150 185165 170 T_(annealing) (in ° C.) 622 658 634 631 618 Dissolution rate at≧30 ≧30 ≧30 107 107 45 ≧30 ≧30 ≧30 pH = 4.5 (in ng/cm² per h) EX. 10 EX.11 EX. 12 EX. 13 EX. 14 EX. 15 EX. 16 EX. 17 EX. 18 EX. 19 EX. 20 EX. 21SiO₂ 43.8 47.1 41.9 48.2 43.2 46.3 45.4 43 44.3 43 47.7 45.6 Al₂O₃ 17.615.7 20.9 19.8 22.5 19.3 18.8 19.7 19.8 21.5 18.4 22.4 CaO 11.9 9.8 14.514 14.3 13.9 13.9 14.1 13.4 14.1 13.8 13.9 MgO 0.5 0.4 0.5 0.5 0.5 0.50.5 0.5 0.7 0.5 0.5 0.5 Na₂O 6.4 6.4 6.1 6 6 6 5.9 6 8.3 6 6 6 K₂O 8.08.0 7.4 7.2 7.1 7.1 7.2 7.2 3.7 7.3 7.3 7.3 Fe₂O₃ 11.3 12.1 8.7 4.2 6.36.8 8.3 9.5 9.3 7.5 6.2 4.2 TOTAL 99.6 99.5 100 99.9 99.9 99.9 100 10099.5 99.9 99.9 99.9 SiO₂ + Al₂O₃ 61.4 62.8 62.8 68 65.7 65.6 64.2 62.763.8 64.5 66.1 68 Na₂O + K₂O 14.4 14.4 13.5 13.2 13.1 13.1 13.1 13.2 1213.3 13.3 13.3 (Na₂O + K₂O)/Al₂O₃ 0.81 0.92 0.65 0.67 0.58 0.66 0.7 0.670.61 0.62 0.72 0.59 T_(log 2.5+) (in ° C.) 1295 1305 1300 1380 1345 13351315 1305 1250 1325 1345 1370 T_(liq) (in ° C.) 1160 1200 1140 1160 11401110 1110 1110 1170 1140 1150 1150 T_(log 2.5) − T_(liq) (in ° C.) 135105 160 220 205 225 205 195 80 175 195 220 T_(annealing) (in ° C.) 615616 635 654 655 645 637 638 644 645 658 Dissolution rate at 60 ≧30 ≧30≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 pH = 4.5 (in ng/cm² per h) EX. 22EX. 23 EX. 24 EX. 25 EX. 26 EX. 27 EX. 28 EX. 29 EX. 30 EX. 31 EX. 32EX. 33 SiO₂ 43.5 43.1 40.3 42.3 43.9 41.5 39.3 47.3 45.3 45.3 44 46.5Al₂O₃ 21.2 22.2 25.1 21.7 24.6 24.7 24.9 18.2 19.2 20.5 22.5 19.2 CaO14.1 14 13.9 13.1 13.2 13.4 13.3 13.9 12.9 12.9 12.7 12.4 MgO 0.5 0.50.5 0.6 0.6 0.6 0.5 0.6 0.8 0.8 0.8 0.8 Na₂O 6 6 6 5.9 5.9 6.2 6.3 8.17.9 8.3 7.9 8.8 K₂O 7.2 7.2 7.2 7.7 7.6 7.6 7.6 3.9 5.7 3.8 3.7 3.9Fe₂O₃ 7.4 6.9 6.9 8.7 4 6 8.1 7.5 7.5 7.4 7.5 7.4 TOTAL 99.9 99.9 99.9100 99.8 100 100 99.5 99.3 99 99.1 99 SiO₂ + Al₂O₃ 64.7 65.3 65.4 64.068.5 66.2 64.2 65.5 64.5 65.8 66.5 65.7 Na₂O + K₂O 13.2 13.2 13.2 13.613.5 12.8 13.9 11.9 13.6 12.1 11.6 12.7 (Na₂O + K₂O)/Al₂O₃ 0.62 0.590.53 0.63 0.55 0.52 0.56 0.65 0.7 0.59 0.52 0.66 T_(log 2.5+) (in ° C.)1325 1335 1330 1300 1370 1330 1295 1270 1270 1280 1285 1280 T_(liq) (in° C.) 1120 1160 1170 1160 1180 1200 1160 1150 1180 1200 1150 T_(log 2.5)− T_(liq) 205 175 160 140 150 95 110 120 100 85 130 (in ° C.)T_(annealing) (in ° C.) 644 650 652 625 618 Dissolution rate at ≧30 ≧30≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 pH = 4.5 (in ng/cm² per h) EX.34 EX. 35 EX. 36 EX. 37 EX. 38 EX. 39 EX. 40 EX. 41 EX. 42 SiO₂ 46.547.7 46.5 48.0 47.1 46 46 43 46.3 Al₂O₃ 19.5 18.9 19.5 19.2 21 20.5 20.123.3 18.8 CaO 11.5 13.6 14.4 13.6 12.6 11.6 14.4 15.7 10.1 MgO 0.7 1.41.4 0.7 0.7 0.7 1.1 0.2 3.5 Na₂O 8.4 7.4 7.3 7.4 7.2 7.4 7.1 7.2 8 K₂O 55 5 5 5 5 5 4.9 5 Fe₂O₃ 7.5 4.8 4.9 4.9 4.9 7.3 4.9 4.9 7.7 TOTAL 99.198.8 99 98.8 98.5 98.5 98.6 99.2 99.4 SiO₂ + Al₂O₃ 66 66.6 66.0 67.268.1 66.5 66.1 66.3 65.1 Na₂O + K₂O 13.4 12.4 12.3 12.4 12.2 12.4 12.112.1 13 (Na₂O + K₂O)/Al₂O₃ 0.69 0.66 0.63 0.6 0.5 0.6 0.6 0.52 0.69T_(log 2.5+) (in ° C.) 1295 1310 1295 1315 1340 1320 1300 1290 1300T_(liq) (in ° C.) 1170 1140 1150 1120 1110 1120 1140 1140 1160T_(log 2.5) − T_(liq) (in ° C.) 125 170 145 195 230 200 160 150 140T_(annealing) (in ° C.) 619 636 636 640 643 633 641 658 Dissolution rateat ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 ≧30 pH = 4.5 (in ng/cm² per h)

[0101] TABLE II Density of the Additive (in % by weight of wool) Degreeof collapse Fiber mineral wool Phosphorus compound Binder at 1000° C.(as % of TEST composition ρ (kg/m³) A B C D E the initial thickness)TEST 1 CONTROL 44 0 0 0 2.5 0 90 TEST 2 CONTROL 41 0 0 3 2.5 0 85 TEST 3EX. 4 48 0 0 0 1.5 0 79 TEST 4 EX. 4 48 4 0 0 1.5 0 40 TEST 5 EX. 33 380 0 0 1.5 0 79 TEST 6 EX. 33 47 0 0 0 2.5 0 77 TEST 7 EX. 33 51 0 0 01.5 0 72 TEST 8 EX. 33 66 0 0 0 1.5 0 71 TEST 9 EX. 33 42 3 0 0 2.5 0 37TEST 10 EX. 33 42 4.4 0 0 2.5 0 26 TEST 11 EX. 33 42 0 3 0 2.5 0 28 TEST12 EX. 33 52 0 0 1 2.5 0 35 TEST 13 EX. 33 80 0 0 1.5 2.5 0 26 TEST 14EX. 33 65 0 0 3 0 0 17 TEST 15 EX. 33 33 0 0 3 1.5 0 35 TEST 16 EX. 3344 0 0 3 2.5 0 18 TEST 17 EX. 33 76 0 0 3 1.5 0 17 TEST 18 EX. 33 91 0 03 1.5 0 17 TEST 19 EX. 33 90 0 0 5 1.5 0 15 TEST 20 EX. 33 100 0 0 5 1.50 14 TEST 21 EX. 41 63 0 0 0 1.6 0 72 TEST 22 EX. 41 48 0 0 0 0 1.6 77TEST 23 EX. 41 56 0 0 3 1.6 0 22 TEST 24 EX. 41 57 0 0 3 0 1.6 20 TEST25 EX. 42 90 0 0 0 2.5 0 48 TEST 26 EX. 42 110 0 0 1.5 2.5 0 33

1. A thermally stable mineral wool capable of dissolving in aphysiological medium, characterized in that it comprises fibers whoseconstituents are mentioned below in the following percentages by weight:SiO₂ 35-60%,  preferably 39-55%  Al₂O₃ 12-27%,  ″ 16-25%  CaO 0-35%, ″3-25% MgO 0-30%, ″ 0-15% Na₂O 0-17%, ″ 6-12% K₂O 0-17%, ″ 3-12% R₂O(Na₂O + K₂O) 10-17%,  ″ 12-17%  P₂O₅ 0-5%,  ″ 0-2%  Fe₂O₃ 0-20%, B₂O₃0-8%,  ″ 0-4%  TiO₂ 0-3%, 

and in that it comprises a phosphorus compound, the phosphorus contentof which, expressed in P₂O₅ form, varies from 0.2%, especially from morethan 0.5%, to 5%, especially to less than 2%, of the total mass offibers, which is capable of reacting above 100° C. with the fibers toform a coating on the surface of the fibers.
 2. The mineral wool asclaimed in claim 1, characterized in that it comprises fibers whoseconstituents are mentioned below in the following percentages by weight:SiO₂ 39-55%,  preferably 40-52%  Al₂O₃ 16-27%,  ″ 16-25%  CaO 3-35%, ″10-25%  MgO 0-15%, ″ 0-10% Na₂O 0-15%, ″ 6-12% K₂O 0-15%, ″ 3-12% R₂O(Na₂O + K₂O) 10-17%,  ″ 12-17%  P₂O₅ 0-5%,  ″ 0-2%  Fe₂O₃ 0-15%, B₂O₃0-8%,  ″ 0-4%  TiO₂ 0-3%, 

and in that MgO is between 0 and 5%, especially between 0 and 2%, whenR₂O≦13.0%.
 3. The mineral wool as claimed in one of the precedingclaims, characterized in that it comprises fibers whose constituents arementioned below in the following percentages by weight: SiO₂ 39-55%, preferably 40-52%  Al₂O₃ 16-25%,  ″ 17-22%  CaO 3-35%, ″ 10-25%  MgO0-15%, ″ 0-10% Na₂O 0-15%, ″ 6-12% K₂O 0-15%, ″ 6-12% R₂O (Na₂O + K₂O)13.0-17%,   P₂O₅ 0-5%,  ″ 0-2%  Fe₂O₃ 0-15%, B₂O₃ 0-8%,  ″ 0-4%  TiO₂0-3%. 


4. The mineral wool as claimed in one of claims 1 to 3, characterized inthat the alkali content (Na₂O+K₂O) of the fibers is such that:13.0%≦R₂O≦15%, especially 13.3%≦R₂O≦14.5%.
 5. The mineral wool asclaimed in one of the preceding claims, characterized in that the Fe₂O₃(total iron) contents of the fibers are such that: 0%≦Fe₂O₃≦5%,preferably 0%≦Fe₂O₃≦3%, especially 0.5%≦Fe₂O₃≦2.5%.
 6. The mineral woolas claimed in one of claims 1 to 4, characterized in that the Fe₂O₃(total iron) contents of the fibers are such that: 5%≦Fe₂O₃≦15%,especially 5%≦Fe₂O₃≦8%.
 7. The mineral wool as claimed in one of thepreceding claims, characterized in that the compositions of the fiberssatisfy the relationship: (Na₂O+K₂O)/Al₂O₃≧0.5.
 8. The mineral wool asclaimed in one of the preceding claims, characterized in that theconstituents of the fibers satisfy the relationship:(Na₂O+K₂O)/Al₂O₃≧0.6, especially (Na₂O+K₂O)/Al₂O₃≧0.7.
 9. The mineralwool as claimed in one of the preceding claims, characterized in thatthe lime and magnesia contents of the fibers are such that: 10%≦CaO≦25%,especially 15%≦CaO≦25% and 0%≦MgO≦5% with preferably 0%≦MgO≦2%,especially 0%≦MgO≦1%.
 10. The mineral wool as claimed in one of claims 1to 8, characterized in that the lime and magnesia contents of the fibersare such that: 5%≦MgO≦10% and 5%≦CaO≦15%, preferably with 5%≦CaO≦10%.11. The mineral wool as claimed in one of the preceding claims,characterized in that the fibers have a dissolution rate of at least 30ng/cm² per hour measured at a pH of 4.5.
 12. The mineral wool as claimedin one of the preceding claims, characterized in that the glasscorresponding to the fibers may be fiberized by internal centrifuging.13. The mineral wool as claimed in one of the preceding claims,characterized in that the coating capable of forming on the surface ofthe fibers essentially consists of an alkaline-earth phosphate.
 14. Themineral wool as claimed in claim 13, characterized in that thealkaline-earth phosphate is a calcium phosphate.
 15. The mineral wool asclaimed in one of the preceding claims, characterized in that thephosphorus compound capable of reacting with the fibers is a compoundwhich decomposes above 100° C., releasing phosphoric acid or phosphoricanhydride.
 16. The mineral wool as claimed in claim 15, characterized inthat the phosphorus compound is chosen from: ammonium phosphates,phosphoric acid and ammonium hydrogenophosphates.
 17. A process formanufacturing mineral wool, characterized in that fibers are essentiallyformed from molten oxides whose constituents are mentioned below in thefollowing percentages by weight: SiO₂ 35-60%,  preferably 39-55%  Al₂O₃12-27%,  ″ 16-25%  CaO 0-35%, ″ 3-25% MgO 0-30%, ″ 0-15% Na₂O 0-17%, ″6-12% K₂O 0-17%, ″ 3-12% R₂O (Na₂O + K₂O) 10-17%,  ″ 12-17%  P₂O₅ 0-5%, ″ 0-2%  Fe₂O₃ 0-20%, B₂O₃ 0-8%,  ″ 0-4%  TiO₂ 0-3%, 

and in that a phosphorus compound, capable of reacting with the fibersin order to form a coating on the surface of the fibers, is thenapplied, especially by spraying or impregnating with a solution.
 18. Useof the mineral wool as claimed in any one of claims 1 to 16 infire-resistant structural systems.